1. Field of the Invention
The invention relates to a reactor switch for switching on and off a reactor which is arranged in a multi-phase electrical high-voltage network and in which switch poles are provided phase-by-phase between the reactor and a part of the network, for example a high-voltage line, which switch poles in each case have at least two series-connected switching chambers in parallel with which at least two series-connected varistors are connected.
2. Discussion of Background
A reactor switch of the type mentioned is disclosed, for example, in US-A-4,831,487. In this reactor switch, metal oxide varistors are connected across the series-connected switching cheers of a switch pole. This results in the recovery voltage which occurs after a quenching process when disconnecting a reactor in a high-voltage network rising only to a specific value. In the case of a restrike which possibly occurs in the case of small contact distances, the gradient of a high-frequency restrike transient can then be limited to a predetermined extent, and the insulation of the reactor can thus be protected against unacceptably high dielectric loads.
It is possible for the restrike not to occur in all the series-connected switching chambers of the switch pole, but only in some of these switching chambers. The restrike current then flows via the restruck switching chambers to those varistors which are connected in parallel with the switching chambers which are free of restrikes and, in general, also via the reactor. Fundamentally, there is no need in this case to be concerned about overloading of the current-carrying varistors in terms of energy, since the reactor limits the restrike current. However, it is also possible for a short-circuit to occur between the reactor switch and the reactor, and for the restrike current no longer to be limited by the reactor. In such a case, overloading, in terms of energy, of the varistors carrying the restrike current possibly cannot be prevented.